Steam engine



M. H. ROBERTS Oct. 15, 1929.

STEAM ENGINE Filed NOV. 19, 1924 INVE TOR I %la;

wlzmw ATTORNEY5 Patented Oct. 15, 1929 UNITED/STATES PATENT, OFFICE -MON'IAGUE H. ROBERTS, F ENGLEWOOD, NEW JERSEY, ASSIGNOR T0 FRANKLIN RAILWAY SUPPLY COMPANY, A CORPORATION OF DELAWARE STEAM ENGINE A'pplication filed November 19, 1924. Serial No. 750,884.

This invention relates to steam engines which are designed with a maximum cut-off which is rather early, say for example at half stroke. The purposes to be served by such an engine are fully understood in this art. An example of this class of engine is disclosed in the Kiesel Patent No. 1,307,821 covering what is generally known as the 50% cut-off locomotive used on the Pennsylvania Railroad and others. o In that device, the valvewhich is actuated by-a'standard form of reversing gear-is designed to give a cut-off at half stroke or less at full gear, and-hence, in order' to properly start the engine, means must be provided to admit steam to the cylinders at starting, In that patent, the'desired result is obtained by providing an auxiliary port in the chest and bushing.

I propose to provide a more simple and economical and more effective arrangement for supplying steam at starting.

How this is obtained is illustrated in the accompanying drawings illustrating the best embodlment of the invention now known to me, and wherein Fig. 1 is a side view of a valve embodying my improvements;

Fig. 2 is an end elevation of Fig. 1'; and

Fig. 3 is a diagrammatic View illustrating the operation of the device.

Referring now to the drawings it will be seen that the valve A is of the spindle .piston type having a reduced or spindle portion 7 intermediate the end portions 'or heads '8.

Each portion 8 at the inner end 8 thereof is turned down in diameter very slightly, say to an extent where the difference in diameters is in the neighborhood of .040". In actual practice I have used a valve having a differen'ce in diameterv of these parts of .046 to very good advantage. As here shown, these facially or peripherally reduced zones 8 extendpractically or actually all around the valve heads 8, 8, and are of, substantially the full-width of the corresponding steam laps of the valve. Notwithstanding their nominal depth the reduced zones 8 8,aiford a supply of steam for starting the engine even when the cylinder ports in the valve chest are covered by the edges of the steam laps,'owing laps. Moreover, the full supply is afforded even when a port is covered practically the full width of the steam lap; because as soon as the shoulder beyond the reduced zone 8 cracks over the edge of the port a distance equal to the nominal depth of the reduction,

the latter affords the maximum opening. If

the valve seat had grooves or slots for the same purpose, the valve would have to uncover the groove a distance equal to the groove depth before the latter would become fully effective which would involvea substantial movement of the valve as compared with what is necessary in the present device where the facial reduction all the way around the valve head is of such a nominal depth. I

On inspection of Fig. 3 it will be seen that the chest is of the usual inside admission and outside exhaust type. In the middle, full line position shown, both the ports 9 and 10 are covered and no steam flows to or from opposite sides of the piston. In the extreme right hand position of the valve, the port 10 is connected to the steam supply port 11 and the port 9 is uncovered for exhaust (in this instance forwardly through the valve). ,In the extreme left hand position of the valve, the port 9 is connected to the port 11 and the port 10 is uncovered for exhaust.

I with the admissionedge of the port. This gives the effect of long cut-ofi' and secures ance becomes ineffective for the admission ofsteam, because its area is insuflicient to pass any material amount of steam in the time afforded for the purpose when the valve is in l'IlOtlOIl, supplying less and'less steam until finally, for all practical purposes, no stem proper starting with substantially the same is supplied therethrough. This occurs after the firstrevolution or two. The width of the reduced zones 8 is such that in no position will all of the ports be completely covered, i. e. steam will always be able to 'flow'to a cylinder.

It will be noted that the width of thereduction in diameter 8 at either end of the valve is not the same, one being wider than the other in correspondence (more or less) with the difierence in width of the corresponding steam laps, to compensate for variation in the movement of the valve gear and provide the same length of steam admission at both ends of the stroke.

lit will be seen that l have provided a simple, and economical way of securing the desired results; and I have found that the ar rangement is very effective, giving a superior automatically graduating efi'ect.

ll claim: I

l. A limited cutoff engine valve having a steam lap and being racially reduced a nominal depth over substantially the entire area of its steam lap, insufficient to give substantial steam admission after starting but all'ording a supply for starting the engine while the port is covered by the edge of said lap.

QIA limited cut-oil steam engine doubleheaded-piston valve with steam laps and having its heads peripherally reduced a nominal depth over substantially the entire area of said steam laps, insuflicienteto give substantial steam admission after starting clearance between the reciprocating member and the bushing in the area of reduced diameter.

6. A fluid distribution valve comprising a ported bushing and a reciprocating piston having a main cut-oil edge and an auxiliary cut-ofi' edge, the effective diameter of the.

having a main cut-off edge and an auxiliary cut-oil edge, there being a clearance between the reciprocating member and the bushing between'the two cut-oil edges, the distance between the main and auxiliary cut-oil edges being appreciably greater than the clearance between the reciprocating member and the bushing.

In testimony signed my name.

Mountable n. ROBERTS,

whereof, I have hereunto but afiording a full supply for starting the engine while the ports are covered by the edges of said laps practically the full widths of the latter.

3. A. piston valve for a limited cut-0E steanr engine, said valve having a steam lap and being peripherally reduced a nominal depth over substantially the entire area of said steam lap, said reduction, however, being ins'uflicient to give substantial steam admission after starting but afiording a supply for starting the engine while the port is covered by the edge of said lap.

4. A fluid distribution valve comprising a ported bushing and a reciprocating piston 1 having a main cut-oil edge and an auxiliary cut-oil edge, both cut-0d edges surrounding the periphery of the reciprocating member, the main and auxiliary cut-oil edges being spaced along the reciprocating inember in the direction of its reciprocation;

5. A fluid distribution valve comprisinga ported bushing and a reciprocating piston having a main cut-ofi' edge and an auxiliary cut-off edge, the auxiliary cut-off edge being formed by reducing the diameter of the reciprocating member between the main and the auxiliary cut-ofi' edges, the distance between the main and the auxiliary cut-oil edges being appreciably greater than the 

